The invention pertains to a method and to an apparatus for testing the brake system of a vehicle having electrically actuated valves.
A brake system for a vehicle in which the brake pressure in the wheel brakes of the vehicle is adjusted by the actuation of a valve assembly as a function of the braking command derived from the driver's actuation of the brake pedal is known from DE-A 41 12 137. In an electrical brake system such as this, it is also provided that, if the electrical control fails, a conventional hydraulic control of the wheel brakes depending on the actuation of the brake pedal can be activated. When the electrical control fails, the driver can therefore decelerate the vehicle and bring it to a stop by actuating the brake pedal. To do this, he must apply the required brake pressure to the wheel brakes by way of the pedal and the brake cylinder of the hydraulic brake system. To ensure the operational reliability of this electrohydraulic brake system, it is necessary for this emergency system to be tested even during normal operating conditions, because a failure of the emergency system after the breakdown of the electrical control can lead to the failure of the entire brake system. A particular problem in this context is the presence of an unacceptable amount of undissolved gas in the brake fluid of the closed emergency brake circuit.